Federal Reserve Board Governor Lael Brainard speaks at the John F. Kennedy School of Government at Harvard University in Cambridge, Massachusetts, U.S., March 1, 2017. REUTERS/Brian Snyder

WASHINGTON (Reuters) - Federal Reserve Board Governor Lael Brainard on Thursday warned it was premature for regulators to revisit liquidity and capital requirements for the largest banks amid growing vulnerabilities in the economy.

Speaking at a conference in Washington, Brainard said rising asset prices and leverage signaled it was too early in the economic cycle to review core rules introduced following the 2007-2009 global financial crisis.

She added it may be appropriate for the Fed to ask banks to build an extra counter-cyclical capital buffer to guard against these emerging risks.